# encoding: utf-8

require 'active_support/inflections'

module ActiveSupport
  # The Inflector transforms words from singular to plural, class names to table
  # names, modularized class names to ones without, and class names to foreign
  # keys. The default inflections for pluralization, singularization, and
  # uncountable words are kept in inflections.rb.
  #
  # The Rails core team has stated patches for the inflections library will not
  # be accepted in order to avoid breaking legacy applications which may be
  # relying on errant inflections. If you discover an incorrect inflection and
  # require it for your application or wish to define rules for languages other
  # than English, please correct or add them yourself (explained below).
  module Inflector
    extend self

    # Returns the plural form of the word in the string.
    #
    # If passed an optional +locale+ parameter, the word will be
    # pluralized using rules defined for that language. By default,
    # this parameter is set to <tt>:en</tt>.
    #
    #   'post'.pluralize             # => "posts"
    #   'octopus'.pluralize          # => "octopi"
    #   'sheep'.pluralize            # => "sheep"
    #   'words'.pluralize            # => "words"
    #   'CamelOctopus'.pluralize     # => "CamelOctopi"
    #   'ley'.pluralize(:es)         # => "leyes"
    def pluralize(word, locale = :en)
      apply_inflections(word, inflections(locale).plurals)
    end

    # The reverse of +pluralize+, returns the singular form of a word in a
    # string.
    #
    # If passed an optional +locale+ parameter, the word will be
    # singularized using rules defined for that language. By default,
    # this parameter is set to <tt>:en</tt>.
    #
    #   'posts'.singularize            # => "post"
    #   'octopi'.singularize           # => "octopus"
    #   'sheep'.singularize            # => "sheep"
    #   'word'.singularize             # => "word"
    #   'CamelOctopi'.singularize      # => "CamelOctopus"
    #   'leyes'.singularize(:es)       # => "ley"
    def singularize(word, locale = :en)
      apply_inflections(word, inflections(locale).singulars)
    end

    # By default, +camelize+ converts strings to UpperCamelCase. If the argument
    # to +camelize+ is set to <tt>:lower</tt> then +camelize+ produces
    # lowerCamelCase.
    #
    # +camelize+ will also convert '/' to '::' which is useful for converting
    # paths to namespaces.
    #
    #   'active_model'.camelize                # => "ActiveModel"
    #   'active_model'.camelize(:lower)        # => "activeModel"
    #   'active_model/errors'.camelize         # => "ActiveModel::Errors"
    #   'active_model/errors'.camelize(:lower) # => "activeModel::Errors"
    #
    # As a rule of thumb you can think of +camelize+ as the inverse of
    # +underscore+, though there are cases where that does not hold:
    #
    #   'SSLError'.underscore.camelize # => "SslError"
    def camelize(term, uppercase_first_letter = true)
      string = term.to_s
      if uppercase_first_letter
        string = string.sub(/^[a-z\d]*/) { inflections.acronyms[$&] || $&.capitalize }
      else
        string = string.sub(/^(?:#{inflections.acronym_regex}(?=\b|[A-Z_])|\w)/) { $&.downcase }
      end
      string.gsub!(/(?:_|(\/))([a-z\d]*)/i) { "#{$1}#{inflections.acronyms[$2] || $2.capitalize}" }
      string.gsub!('/', '::')
      string
    end

    # Makes an underscored, lowercase form from the expression in the string.
    #
    # Changes '::' to '/' to convert namespaces to paths.
    #
    #   'ActiveModel'.underscore         # => "active_model"
    #   'ActiveModel::Errors'.underscore # => "active_model/errors"
    #
    # As a rule of thumb you can think of +underscore+ as the inverse of
    # +camelize+, though there are cases where that does not hold:
    #
    #   'SSLError'.underscore.camelize # => "SslError"
    def underscore(camel_cased_word)
      return camel_cased_word unless camel_cased_word =~ /[A-Z-]|::/
      word = camel_cased_word.to_s.gsub('::', '/')
      word.gsub!(/(?:([A-Za-z\d])|\b)(#{inflections.acronym_regex})(?=\b|[^a-z])/) { "#{$1}#{$1 && '_'}#{$2.downcase}" }
      word.gsub!(/([A-Z\d]+)([A-Z][a-z])/,'\1_\2')
      word.gsub!(/([a-z\d])([A-Z])/,'\1_\2')
      word.tr!("-", "_")
      word.downcase!
      word
    end

    # Tweaks an attribute name for display to end users.
    #
    # Specifically, +humanize+ performs these transformations:
    #
    #   * Applies human inflection rules to the argument.
    #   * Deletes leading underscores, if any.
    #   * Removes a "_id" suffix if present.
    #   * Replaces underscores with spaces, if any.
    #   * Downcases all words except acronyms.
    #   * Capitalizes the first word.
    #
    # The capitalization of the first word can be turned off by setting the
    # +:capitalize+ option to false (default is true).
    #
    #   humanize('employee_salary')              # => "Employee salary"
    #   humanize('author_id')                    # => "Author"
    #   humanize('author_id', capitalize: false) # => "author"
    #   humanize('_id')                          # => "Id"
    #
    # If "SSL" was defined to be an acronym:
    #
    #   humanize('ssl_error') # => "SSL error"
    #
    def humanize(lower_case_and_underscored_word, options = {})
      result = lower_case_and_underscored_word.to_s.dup

      inflections.humans.each { |(rule, replacement)| break if result.sub!(rule, replacement) }

      result.sub!(/\A_+/, '')
      result.sub!(/_id\z/, '')
      result.tr!('_', ' ')

      result.gsub!(/([a-z\d]*)/i) do |match|
        "#{inflections.acronyms[match] || match.downcase}"
      end

      if options.fetch(:capitalize, true)
        result.sub!(/\A\w/) { |match| match.upcase }
      end

      result
    end

    # Capitalizes all the words and replaces some characters in the string to
    # create a nicer looking title. +titleize+ is meant for creating pretty
    # output. It is not used in the Rails internals.
    #
    # +titleize+ is also aliased as +titlecase+.
    #
    #   'man from the boondocks'.titleize   # => "Man From The Boondocks"
    #   'x-men: the last stand'.titleize    # => "X Men: The Last Stand"
    #   'TheManWithoutAPast'.titleize       # => "The Man Without A Past"
    #   'raiders_of_the_lost_ark'.titleize  # => "Raiders Of The Lost Ark"
    def titleize(word)
      humanize(underscore(word)).gsub(/\b(?<!['’`])[a-z]/) { $&.capitalize }
    end

    # Create the name of a table like Rails does for models to table names. This
    # method uses the +pluralize+ method on the last word in the string.
    #
    #   'RawScaledScorer'.tableize # => "raw_scaled_scorers"
    #   'egg_and_ham'.tableize     # => "egg_and_hams"
    #   'fancyCategory'.tableize   # => "fancy_categories"
    def tableize(class_name)
      pluralize(underscore(class_name))
    end

    # Create a class name from a plural table name like Rails does for table
    # names to models. Note that this returns a string and not a Class (To
    # convert to an actual class follow +classify+ with +constantize+).
    #
    #   'egg_and_hams'.classify # => "EggAndHam"
    #   'posts'.classify        # => "Post"
    #
    # Singular names are not handled correctly:
    #
    #   'calculus'.classify     # => "Calculu"
    def classify(table_name)
      # strip out any leading schema name
      camelize(singularize(table_name.to_s.sub(/.*\./, '')))
    end

    # Replaces underscores with dashes in the string.
    #
    #   'puni_puni'.dasherize # => "puni-puni"
    def dasherize(underscored_word)
      underscored_word.tr('_', '-')
    end

    # Removes the module part from the expression in the string.
    #
    #   'ActiveRecord::CoreExtensions::String::Inflections'.demodulize # => "Inflections"
    #   'Inflections'.demodulize                                       # => "Inflections"
    #   '::Inflections'.demodulize                                     # => "Inflections"
    #   ''.demodulize                                                  # => ""
    #
    # See also +deconstantize+.
    def demodulize(path)
      path = path.to_s
      if i = path.rindex('::')
        path[(i+2)..-1]
      else
        path
      end
    end

    # Removes the rightmost segment from the constant expression in the string.
    #
    #   'Net::HTTP'.deconstantize   # => "Net"
    #   '::Net::HTTP'.deconstantize # => "::Net"
    #   'String'.deconstantize      # => ""
    #   '::String'.deconstantize    # => ""
    #   ''.deconstantize            # => ""
    #
    # See also +demodulize+.
    def deconstantize(path)
      path.to_s[0, path.rindex('::') || 0] # implementation based on the one in facets' Module#spacename
    end

    # Creates a foreign key name from a class name.
    # +separate_class_name_and_id_with_underscore+ sets whether
    # the method should put '_' between the name and 'id'.
    #
    #   'Message'.foreign_key        # => "message_id"
    #   'Message'.foreign_key(false) # => "messageid"
    #   'Admin::Post'.foreign_key    # => "post_id"
    def foreign_key(class_name, separate_class_name_and_id_with_underscore = true)
      underscore(demodulize(class_name)) + (separate_class_name_and_id_with_underscore ? "_id" : "id")
    end

    # Tries to find a constant with the name specified in the argument string.
    #
    #   'Module'.constantize     # => Module
    #   'Test::Unit'.constantize # => Test::Unit
    #
    # The name is assumed to be the one of a top-level constant, no matter
    # whether it starts with "::" or not. No lexical context is taken into
    # account:
    #
    #   C = 'outside'
    #   module M
    #     C = 'inside'
    #     C               # => 'inside'
    #     'C'.constantize # => 'outside', same as ::C
    #   end
    #
    # NameError is raised when the name is not in CamelCase or the constant is
    # unknown.
    def constantize(camel_cased_word)
      names = camel_cased_word.split('::')

      # Trigger a built-in NameError exception including the ill-formed constant in the message.
      Object.const_get(camel_cased_word) if names.empty?

      # Remove the first blank element in case of '::ClassName' notation.
      names.shift if names.size > 1 && names.first.empty?

      names.inject(Object) do |constant, name|
        if constant == Object
          constant.const_get(name)
        else
          candidate = constant.const_get(name)
          next candidate if constant.const_defined?(name, false)
          next candidate unless Object.const_defined?(name)

          # Go down the ancestors to check if it is owned directly. The check
          # stops when we reach Object or the end of ancestors tree.
          constant = constant.ancestors.inject do |const, ancestor|
            break const    if ancestor == Object
            break ancestor if ancestor.const_defined?(name, false)
            const
          end

          # owner is in Object, so raise
          constant.const_get(name, false)
        end
      end
    end

    # Tries to find a constant with the name specified in the argument string.
    #
    #   'Module'.safe_constantize     # => Module
    #   'Test::Unit'.safe_constantize # => Test::Unit
    #
    # The name is assumed to be the one of a top-level constant, no matter
    # whether it starts with "::" or not. No lexical context is taken into
    # account:
    #
    #   C = 'outside'
    #   module M
    #     C = 'inside'
    #     C                    # => 'inside'
    #     'C'.safe_constantize # => 'outside', same as ::C
    #   end
    #
    # +nil+ is returned when the name is not in CamelCase or the constant (or
    # part of it) is unknown.
    #
    #   'blargle'.safe_constantize  # => nil
    #   'UnknownModule'.safe_constantize  # => nil
    #   'UnknownModule::Foo::Bar'.safe_constantize  # => nil
    def safe_constantize(camel_cased_word)
      constantize(camel_cased_word)
    rescue NameError => e
      raise if e.name && !(camel_cased_word.to_s.split("::").include?(e.name.to_s) ||
        e.name.to_s == camel_cased_word.to_s)
    rescue ArgumentError => e
      raise unless e.message =~ /not missing constant #{const_regexp(camel_cased_word)}\!$/
    end

    # Returns the suffix that should be added to a number to denote the position
    # in an ordered sequence such as 1st, 2nd, 3rd, 4th.
    #
    #   ordinal(1)     # => "st"
    #   ordinal(2)     # => "nd"
    #   ordinal(1002)  # => "nd"
    #   ordinal(1003)  # => "rd"
    #   ordinal(-11)   # => "th"
    #   ordinal(-1021) # => "st"
    def ordinal(number)
      abs_number = number.to_i.abs

      if (11..13).include?(abs_number % 100)
        "th"
      else
        case abs_number % 10
          when 1; "st"
          when 2; "nd"
          when 3; "rd"
          else    "th"
        end
      end
    end

    # Turns a number into an ordinal string used to denote the position in an
    # ordered sequence such as 1st, 2nd, 3rd, 4th.
    #
    #   ordinalize(1)     # => "1st"
    #   ordinalize(2)     # => "2nd"
    #   ordinalize(1002)  # => "1002nd"
    #   ordinalize(1003)  # => "1003rd"
    #   ordinalize(-11)   # => "-11th"
    #   ordinalize(-1021) # => "-1021st"
    def ordinalize(number)
      "#{number}#{ordinal(number)}"
    end

    private

    # Mounts a regular expression, returned as a string to ease interpolation,
    # that will match part by part the given constant.
    #
    #   const_regexp("Foo::Bar::Baz") # => "Foo(::Bar(::Baz)?)?"
    #   const_regexp("::")            # => "::"
    def const_regexp(camel_cased_word) #:nodoc:
      parts = camel_cased_word.split("::")

      return Regexp.escape(camel_cased_word) if parts.blank?

      last  = parts.pop

      parts.reverse.inject(last) do |acc, part|
        part.empty? ? acc : "#{part}(::#{acc})?"
      end
    end

    # Applies inflection rules for +singularize+ and +pluralize+.
    #
    #  apply_inflections('post', inflections.plurals)    # => "posts"
    #  apply_inflections('posts', inflections.singulars) # => "post"
    def apply_inflections(word, rules)
      result = word.to_s.dup

      if word.empty? || inflections.uncountables.include?(result.downcase[/\b\w+\Z/])
        result
      else
        rules.each { |(rule, replacement)| break if result.sub!(rule, replacement) }
        result
      end
    end
  end
end
